Time-course analysis of antibody response by EITB and ELISA before and after chemotherapy in sheep infected with Fasciola gigantica.

The time-course analysis of the antibody response to Fascicola gigantica infection in sheep was studied by enzyme-linked immunosorbent assay (ELISA) and enzyme-linked immunoelectrotransfer blot (EITB). Sera from sheep experimentally infected with F. gigantica were reacted with excretory-secretory antigens of the worm before and after chemotherapy with oxyclozanide. In ELISA, there was a significant increase in anti-Fasciola antibody by 2 weeks after infection and there was a sharp decrease in antibody titer by 4 weeks after treatment. By EITB, the infected sheep sera recognised four polypeptides in the range of 43-75 kDa as early as 2 weeks after infection, with more polypeptides being recognised as the infection progressed. Recognition of an 87 kDa antigen was lost by 2 weeks after treatment and is therefore a good marker for treatment efficacy. Comparative immunoblotting with sheep anti-Paramphistomum, anti-Dicrocoelium and anti-Fasciola sera revealed that the 17 kDa, 21 kDa, 57 kDa and 69 kDa proteins are specific to fasciolosis and are good antigens for early and specific immunodiagnosis of F. gigantica infection in sheep.